Split Active Asteroid P/2016 J1 (PANSTARRS)

Abstract

We present a photometric and astrometric study of the split active asteroid P/2016 J1 (PANSTARRS). The two components (hereafter J1-A and J1-B) separated either $\sim$1500 days (2012 May to June) or 2300 days (2010 April) prior to the current epoch, with a separation speed $V_{\mathrm{sep}}=0.70\pm 0.02$ m s${}^{-1}$ for the former scenario, or $0.83\pm 0.06$ m s${}^{-1}$ for the latter. Keck photometry reveals that the two fragments have similar, Sun-like colors which are comparable to the colors of primitive C- and G-type asteroids. With a nominal comet-like albedo, $p_R=0.04$, the effective, dust-contaminated cross sections are estimated to be 2.4 km${}^2$ for J1-A, and 0.5 km${}^2$ for J1-B. We estimate that the nucleus radii lie in the range $140\lesssim R_{\mathrm{N}}\lesssim 900$ m for J1-A and $40\lesssim R_{\mathrm{N}}\lesssim 400$ m, for J1-B. A syndyne-synchrone simulation shows that both components have been active for 3 to 6 months, by ejecting dust grains at speeds $\sim$0.5 m s${}^{-1}$ with rates $\sim$1 kg s${}^{-1}$ for J1-A and 0.1 kg s${}^{-1}$ for J1-B. In its present orbit, the rotational spin-up and devolatilization times of 2016 J1 are very small compared to the age of the solar system, raising the question of why this object still exists. We suggest that ice that was formerly buried within this asteroid became exposed at the surface, perhaps via a small impact, and that sublimation torques then rapidly drove it to break-up. Further disintegration events are anticipated due to the rotational instability.

21 pages, 3 figures. Accepted by AJ

References in corpus (5)

• Main-Belt Comet P/2008 R1 (Garradd)
• Disintegrating Asteroid P/2013 R3
• Cometary Dust Trail Associated with Rosetta Mission Target: 67P/Churyumov-Gerasimenko
• Fast Rotation and Trailing Fragments of the Active Asteroid P/2012 F5 (Gibbs)
• Fragmentation Kinematics in Comet 332P/Ikeya-Murakami

Cited by in corpus (7)

• The Main Belt Comets and Ice in the Solar System
• Prediscovery Observations and Orbit of Comet C/2017 K2 (PANSTARRS)
• Multiple Outbursts of Asteroid (6478) Gault
• Dynamically correlated minor bodies in the outer Solar system
• New Insights into Interstellar Object 1I/2017 U1 (`Oumuamua) from SOHO/STEREO Nondetections
• Detailed Characterization of Low Activity Comet 49P/Arend-Rigaux
• Fragment Dynamics in Active Asteroid 331P/Gibbs